Scientists advise against harvesting shellfish due to large “red tide” in Southeast Alaska

Published: June 22, 2012

State health officials remind public about risks

ANCHORAGE — Warm weather combined with an increasingly large algae bloom in Southeast Alaska has scientists advising extra caution to would-be recreational shellfish harvesters. Water samples taken from around Etolin Island show increasing levels ofAlexandrium algae, which produces paralytic shellfish poisoning (PSP) in shellfish. Tests have also shown a slight increase in Alexandrium levels on the west coast of Prince of Wales Island as well as extremely high levels around Juneau.

Scientists have also identified unsafe levels of three different species of Dinophysis algae, which produces diarrhetic shellfish poisoning (DSP), in samples from around Ketchikan. DSP can cause diarrhea, PSP can cause paralysis.

“These Alexandrium levels are similar to what we saw last year when we had such high levels of PSP toxins in shellfish,” said Kate Sullivan, with the University of Alaska Southeast and co-founder of the Alaska Harmful Algal Bloom Partnership (AHAB). “Last summer we had a number of cases, including four people who needed to be hospitalized. We want people to be extra cautious and remember that the only safe shellfish is the kind you buy at the store.”

Early signs of paralytic shellfish poisoning often include tingling of the lips and tongue. Symptoms may progress to tingling of fingers and toes, then loss of control of arms and legs, followed by difficulty breathing. Death can result in as little as two hours.

All locally harvested shellfish — including clams, mussels, oysters, geoducks and scallops — can contain paralytic shellfish poison. Crabmeat is not known to contain the PSP toxin, but crab guts can contain unsafe levels of toxin and should be discarded. There is no way to tell if a beach is safe for harvesting by looking at it. Toxins can be present in large amounts even if the water looks clear. Also, the toxin can remain in shellfish long after the algae bloom is over.PSP cannot be cooked, cleaned or frozen out of shellfish. Commercially grown shellfish is tested and considered safe.

Paralytic shellfish poisoning is considered a public health emergency. Suspected cases must be reported immediately to the Section of Epidemiology by health care providers at 907-269-8000 during work hours or 800-478-0084 after hours.